Mugain ingen Failbi

Mugain ingen Failbi's father was Failbe mac Domnail of Ui Bairrche and her mother was Ethne ingen Crundmael.  Her paternal grandfather was Domnaill mac Cormaic of Ui Bairrche; her maternal grandparents were Crundmael mac Ronain of Laigin and Failend ingen Suibne.  She was an only child.

They had a daughter named Conchenn ingen Cellaig Cualain of Laigim.